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9c04742e73
When opening a legacy rawmidi device for a UMP, it may re-open an existing rawmidi device for appending to a substream, leading to a lockdep warning due to rmidi->open_mutex taken twice -- but the rawmidi devices are completely individual, hence it's a false-positive. For avoiding the warning, modify the helper to open a rawmidi instance with a proper locking subclass from the UMP legacy open. Unfortunately, there is no good way to achieve it with guard(), so reverted to the manual mutex calls again. Reported-by: syzbot+d10d58fc99caa0489796@syzkaller.appspotmail.com Closes: https://lore.kernel.org/6a6a9634.57649fcc.360844.000b.GAE@google.com Link: https://patch.msgid.link/20260806101352.1291581-1-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de>